Sintering apparatus



Feb. 13, 1940. H. J. sTEHLI SINTERING APPARATUS Filed Oct. 25, 1938 gn Q-Jgw uw?? nw resented Feb. 1 3, 1940 UNITED L STATES PATENT Aori-Icasm'rnamc. APPARATUS Henry J. stehn, cedar Grove, N. J. Appueaaen octoberz5, 193s, serial No. 236,840

solenne.

My invention relates to sintering lapparatus, both to machines of theDwight 8: Lloyd continuous type, and to the intermittent or pan type.

sintering machines of the continuous type con- 5 sist of a suction boxor a series of suction boxes over which pass pallets or cars having apervious bottom and filled with a charge of ore. 'Ihe pallets orcarsvmake very close contact with the top of the suction boxes to forman air seal, the l effect vof the suction being to draw the cars palletsdownwardly onto the edge of the suction boxes to form an effective seal.The charge of ore in the cars is combustible or is admixed with a fueland,lupon being ignited at the top surface as l it passes over thesuction boxes, the down draft of air causes the charge of material onthe pallets or cars to burn progressively downwardly from the top to'the bottom of the charge. v The pan type sintering apparatus consists ofa go pot orvpan provided ,with a grate bottom and having an exhaust boxunderneath the grate. In operation, the charge is placed on the grates,levelled off and. ignited at the top surface, and air is drawn throughthe bed to burn the fuel as in 25 the continuous type. l In theoperation of sintering apparatus, the

gases passing into the suction box are hot and generally full of dust,acid constituents and, sometimes, sublimedsulphur, volatilized metals or30 metallic oxides, or other corrosive materials, de-

pending upon the charge on the apparatus. These h ot gases are,therefore, very destructive to the blowers and it has therefore beennecessaryto use fans of the centrifugal type having wide clear- 35 ancesand low` mechanical efficiencies. Under certain conditions as, forexample, when chlorine gas is liberated during the roasting ,orsintering,

such centrifugal fans are rapidly attacked unless built of expensivematerial such as corrosion re- 40 sistant alloys. In the above types ofsintering apparatus the amount of suction or pressuredifference betweenthe top and bottom of the charge is limited. For example, it is dimcultto obtain a vacuum much greater than 20 inches of water,

45 due to cost, and there is generally an upper limit to the vacuum ofabout 28 inches of water.

Efforts have been made to overcome these limitations by supplying airunder pressure'to the top of the sintering machine and thereby to runthe 50 machine under pressure rather than under vacuum. For this purposeit has been proposed to provide a pressure hood above the sinteringmachine and fitting tightly on the upper edges of the moving cars orpallets. Although this avoids 55 the necessity of passing hot gasesthrough fans or (Cl. 26S-21) blowers or exhausters, other difficultieshave been encounteredwhich have proven substantial obstacles to thesuccessful operation of the machine.

Among these diiiiculties is that of making a satisfactory seal jointbetween the cars or pallets 5 and the pressure wind box or hood abovethe machine. To provide a seal with a wind box, it is necessary to havecross partitions at each end of the cars or pallets to make an end sealas well as to seal the sides of the cars to the wind box. These crosspartitions interfere with the even feeding of the cars and must be sweptfree from the charging material in order to form a tight seal and aresubject to rapid destruction by the flame of the ignition burner andalso to warping from the effect 15 of heat. The effectiveness of theseals is, therefore, subject to impairment due to the above and othercauses. The pressure hood or wind box also serves to prevent accessbeing had to the material being sintered so that if local conditionsinterfere with proper sintering as, for example, if blow holes develop,they cannot be quickly detected and plugged. l

In my present invention I avoid all of the above difficulties of thesuction and wind box arrangements and provide a sintering apparatus inwhich air for combustion may be supplied under pressure, therebyavoiding the necessityl of handling or exhausting hot exhaust gases, andin which a pressure differential through the sintering bed of 30 anydesired magnitude may be maintained, and in which the sintering be'd isopen and accessible to the operator.

In my invention I enclose the sintering apparatus, or a number ofsintering apparatus, each of which is provided with a collection orexhaust box or system similar to the suction boxes heretofore used, in aroom or structure maintained under air pressure. 'I'he pressure of theexhaust gases leaving the sintering apparatus may be 40 either atatmospheric pressure or slightlyabove or below atmospheric pressure,depending upon the stack conditions if the exhaust gases pass directlytoa stack, or upon the conditions in the treating apparatus if the gasesare subjected to. further treatment. Air under suitable pressure iscontinuously supplied to the room o; enclosure within which thesintering apparatus is operated.

-Ore or other charging material is also continuously supplied anddistributed on the upper surl face of the charge. holders. 'I'he orematerial is ignited from a burner, or other suitable means, in itsinitialv passage or entrance over the' exhaust boxes and thereafterdownward combustion is maintained by the air under pressure passing '5 1downwardly through the ore charges to the offtake or exhaust boxes. Thesintered material discharged from the sintering apparatus is then takenfrom the enclosure or room by a water seal, air lock or other dischargemeans. Air may be supplied to the building or structure under anysuitable pressure to maintain the proper draft. A pressure of 2 to 3pounds per square inch will usually be the maximum required. Theoperators for running the sintering apparatus may, therefore, be withinthe enclosure or room inasmuch as this pressure will cause nosubstantial discomfort.

The various features of the invention are illustrated inthe accompanyingdrawing, in which- Fig. 1 is a diagrammatic vertical section of acontinuous sintering apparatus embodying my invention. y

Fig. 2 is a similar section of a part of a sintering apparatus embodyinga different arrangement of the section box.

In the apparatus show-n in Fig.' 1, a sintering machine, comprising achain of pallets or cars IIJ passing between pairs of supporting 'wheelsII and I2, is positioned within a room or .enclosure I 3. In its upperflight the chain of pallets passes over and is supported on thestructure of an exhaust box I4 having an outlet or exhaust ue I5 leadingto a stack I6 outside of the enclosure I3. Air under pressure issupplied tothe enclosure or room I3 by means of a blower I1 whichdelivers through a delivery pipe I8 into the enclosure I3. The air underpressure thus supplied to the enclosure I3 passes downwardly through theupper flight of cars or pallets into the exhaust box I4, as indicated bythe arrows, and thence into the exhaust flue I5 leading to the stack I6.

The material to be sintered as, for example, ores, ore concentrates,fuel, colloids or other reagents, may be supplied from one or more binsI9 by means of automatic feeders 20 to a common conveyor 2| and thencedelivered to an open ended hopper 23 mounted in the roof of the buildingI3, and having its lower end within the build-' ing. The material is fedfrom the lower end of the hopper 22 by means of an automatic feeder 23driven by a belt or other transmission 24 from the driving wheel II ofthe sintering machine. 'I'his ensures a speed proportionate to the speedof the sintering machine. -The feed, however, may be regulated by meansof a control gate 25. The mass of material in the hopper is generallysumcient to seal the room against undue loss of air but if not asuitable sealing device may be provided.

The material from the hopper 48 passes into a mixer or pelletizer 26from whence it is-delivered to a feed hopper 21 at the front end of thesintering machine and by which it is spread in an even bed onto thetraveling pallets or cars. 'Ihe material thus spread onto the palletspasses beneath a burner 28 where it is ignited and, in its furtherpassage over the exhaust box I4, is burned in a descending zone until itis completely sintered.

As the pallets pass over the wheels I2 at the delivery end of thesintering machine, they drop the sintered material into a water seal 29from which it may be lifted by a bucket or other type of conveyor 30outside of the building and delivered into a car 3|, or otherreceptacle.

The wall of the building I3 extends into the water seal 29', as at 32,to maintain the seal while permitting the sintered material to passtherethrough. l

In the modification shown in Fig. 2, the exhaust box i4 is provided withpartitions n which divide the exhaust box into a number of separatechambers 34. The chambers immediately below the ignition burner 28exhaust through a pipe Il,

the chambers in the central part exhaust through a pipe 36, and the endchambers exhaust through a pipe 31. 'Ihis permits separate treatment ofthe different gases. For example, the gases being exhausted through thepipe 3B from the central part of the sintering apparatus may be rich insulphur dioxide and, therefore, useful directly for acid making. Thegases passing through the exhaust pipe 35, from immediately beneath theignition burners, may contain gases unsuitable dlrectly for the makingof acid, and may be treated specially. 'Ihe gases passingthrough the.exhaust pipe 31 may be free of anyuseless or deleterious materials andmay, therefore, be exhausted directly to the atmosphere. It will beunderstood, of course, that the particularl treatment of the exhaustgases may vary.

It will be understood that the illustration in the drawing is merely byway of example, and that any suitable enclosure may be employed, eitherabout each individual sintering machine or, if more than one sinteringmachine is in operation at a time, a single enclosure may be employedfor several such machines.

Through the above invention I am able to maintain a relatively high airpressure on thematerial being sintered and avoid the diiiiculties ofmaintaining an air tight seal between the traveling pallets and thepressure hood. Inasmuch as the air is supplied while cool, dense andfree from dust and corrosive materials, eiiicient blowers such as Turboblowers, rotary blowers, or other positive pressure blowers havingslight clearance spaces and high mechanical eiciencies may be employed.Moreover,as the air is blown into the building in largeV quantities andthence passes into and through the sintering machine, it tends to clearthe atmosphere within the building Yor enclosure of dust, fumes, etc.,which are carried into and through thesintering bed. This makes workingconditions about the sintering machine much better than would bejthecase if a pressure hood or a suction apparatus were employed.

In my invention it will also be notedl that by partitioning the exhaustboxes, gases of diierent qualities may be withdrawn from the differentparts of the sintering machine without requiring a fan or exhauster foreach gas withdrawn.

What I claim is:

1. sintering apparatus which comprises a sintering machine havingsuccessive moving pallets for supporting a bed of material to besintered, an exhaust box below and sealed to the pallets of saidsintering machine, a room enclosing said sintering machine, and means tosupply air under pressure to said room.

2. sintering apparatus which comprises asininganumberofpartitiomdlvldingitintosepu' l arate compartments, a roomenclosing said sintering machine, means to supply air under pressure tosaid room, and means to supply sintering material to said room.

4. sintering apparatus which comprises a sintering machine havingsuccessive moving pallets to support material to be sintered, means toignite the material on said pallets, an exhaust box below' and sealed tosaid pallets, said exhaust box having a number of partitions dividing itinto separate compartments, a room enclosing said sintering machine,means to supply air under pressure to said rooni, means to supplysintering material to said room and to said sintering machine therein,and means to withdraw sintering material from said room.

5. sintering apparatus which comprises a sintering machine havingsuccessive moving pallets to vsupport material to be sintered, means toignite the material on said pallets, an exhaust box below and sealed tosaid pallets, said exhaust box having a number of partitions dividing itinto separate compartments, a room enclosing said sintering machine,means to supply air under pressure to said room, and a water seal intowhich sintered material is delivered and from which it may be withdrawnoutside of said room.

6. sintering apparatus which 'comprises a room, a sintering machine insaid room, said sintering machine having continuous moving means tosupport material to be sintered, an exhaust box below said means, meansfor suplesser pressure than that o! said room,

plying material to be sintered to said continuously moving sinteringmeans. and means for supplying air under pressure to said room.

7. sintering apparatus which comprises a room, a sintering machine insaid room having a moving grate for the support of material to besintered and an exhaust box below and sealed to said grate, means tomaintain said room and the upper part of said grate at super-atmosphericpressure, and means to conduct exhaust gases from said exhaust'box atapproximately atmospheric pressure.

8. A process of prises supplying said sintering material whichcommaterials to a room under super-atmospheric pressure, spreading saidmaterial in a layer in said room and continuously passing said layerover an exhaust chamber at a igniting said layer as it passes over saidexhaust chamber and burning it with a down draft of air.

9. A process of sintering material which comprises supplying saidmaterials toa room under super-atmospheric'pressure, spreading saidmaterial in a layer in said room and continuously passing said layerover an exhaust chamber at a lesser pressure than that of said room,igniting said layer as it passes over said exhaust chamber and burningit with a down draft o! air, and separating the exhaust gases in saidchamber into separate streams at successive distances in its path oftravel.

HENRY J. BTEHIJ.

